<template>      
    <div class="count">
       <h2>当前求和为：{{ sum }}</h2>
       <select v-model.number="n">
          <option value="1">1</option>
          <option value="2">2</option>
          <option value="3">3</option>
       </select>
       <button @click="add">加</button>
       <button @click="minus">减</button>
    </div>
</template>

<script lang="ts"  setup name="Count">  //脚本标签
   import {ref} from 'vue'

   let sum = ref(1)//当前求和
   let n = ref(1)//用户选择的数据

   function add(){
    sum.value += n.value
   }
   function minus(){
    sum.value -= n.value
   }

</script>

<style>
  .count {
    background-color: skyblue;
    padding: 10px;
    border-radius:10px;
    box-shadow: 0 0 10px;
  }
  select,button {
    margin: 0 5px;
    height: 25px;
  }
</style>